The Erb family of receptors is transmembrane receptor tyrosine kinases involved in a wide range of signal transduction and cellular functions, and have become a very fruitful area for the successful development of drugs to treat cancer. ErbB2 is found to be significantly over expressed in 20-30% of human breast cancers and is associated with a poor prognosis. EGFR (erbB1) has also been targeted for the treatment of cancer, and several agents have been approved with this mode of action. (Med. Res. Rev. 2006, 26, 569.)
Pyridopyrimidine nucleus is a pharmacophoric scaffold and represents a class of heterocyclic compounds with a wide range of biological applications. Many of them are widely used as anticonvulsant, sedative, anti-depressive, anti-pyretic agents. Some heterocycles containing pyrido pyrimidine moiety were reported to possess anti-inflammatory, antiviral, antimicrobial, and anti-tumor activities. Other than their biological importance, pyrido pyrimidine derivatives are valuable for the preparation of fused ring compounds, such as triazolopyrimidines, thieno-pyrimidines, thiazolo-pyrimidines, and pyridopyrimidines. It has been noticed that introduction of an 4-ethynyl phenyl ring at 3-position of pyrido pyrimidines core tends to exert profound influence in conferring novel biological activities like anticancer activity in these molecules. Although many methods for synthesizing pyridopyrimidines ring systems have been reported, they continue to receive a great deal attention.
Pyrido[2,3-d]pyrimidine nucleus containing compounds have shown diverse biological profiles, great specificity for individual subgroups of receptor tyrosine kinases and also inhibit non-receptor tyrosine kinases such as Abl, Akt or cyclin kinases. Another target for these derivatives is dihydrofolate reductase inhibition, e.g. piritrexim (Cancer Biol. Ther. 2005, 4, 1125-1132).
A number of pyrido[2,3-d]pyrimidine nucleoside analogues have been either used clinically as tumour agents or evaluated in clinical studies. These compounds have been demonstrated to specifically inhibit tyrosine kinases and participating in a number of cellular signaling events including mitogenesis processes. (Bioorg. Med. Chem. 2007, 15, 1659-1669).
The PI3K/Akt pathway has attracted much attention in the cancer research community due to its involvement in multiple cell survival, growth, energy metabolism, and proliferation pathways.
Recently a wide range of pyridopyrimidine amines, have been synthesized which were tested against different cell lines which inhibit the phosphorylation of Akt isozymes in C33a cancer cells (Bioorg. Med. Chem. Lett. 2008, 18, 4186-4190).